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The ultimate starting point for any transformer assessment is the oil analysis. Like blood testing in human beings, it’s an essential indicator of good health.

DNV GL provides independent oil laboratory services covering sampling, analysis and interpretation. Our reports provide you with data on the condition of the oil, information on possible defects, and recommendations for appropriate action such as specific advanced diagnosis and analysis, and time to next analysis. We also offer database services such as trend analysis and alerts, so you can ensure timely replacements and avoid unexpected failures. You can also call on us for a second opinion on oil analysis results from other laboratories.

Standards-based analysis and database services
Wherever available, we follow international standards such as IEC 60422 and IEC 60599. All the data we gather on equipment and from analyses is stored in a database, which is linked to an expert system with knowledge rules based on both the relevant standards and DNV GL's proprietary expertise. The database contains over 50,000 analysis records of over 8,000 transformers, switchgears and bushings. To provide optimal advice, we constantly improve the expert system’s knowledge rules and verify them in real-world conditions.

Specifically our analyses include and cover:

dissolved gas analysis (DGA)

physical and chemical properties

furfural analysis

corrosive sulphur compounds.

For users of computerised maintenance management software, such as Cascade , we also provide support in implementing analysis and interpretation in software algorithms and criteria.

What you receive
Analysis is carried out in our laboratory in Arnhem, the Netherlands. Once complete, you will receive a detailed report covering the condition of the oil and relevant components, along with our recommended actions. We will inform your operational management of any indications of irregular behaviour or incipient faults – such as partial discharge or thermal faults – as soon as possible.

In addition, customers with regular analysis contracts have internet access to their data contained in the DNV GL database.

DNV GL has years of worldwide experience in the electricity industry. Thus we can base our findings and judgements on a thorough understanding of transformers – including their degradation process and failure mechanisms, as well as the chemistry and physics of transformer oil. This impartial knowledge allows you to develop effective strategies and procedures for operation, maintenance and replacement, while controlling quality and potential risks.